Search

Copyright of Óptica Pura y Aplicada is the property of Sociedad Espanola de Optica and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This document is a newsletter from the Spanish Society of Optics (SEDOPTICA) highlighting their recent activities and achievements. The newsletter discusses the active participation of SEDOPTICA members in international forums, the addition of new collaborating companies, and the recognition of the quality of their journal, Óptica Pura y Aplicada. It also mentions various activities and events organized by SEDOPTICA, including programs for young researchers, conferences on the history of optics, and the publication of educational books. The newsletter concludes with information about the renewal of the journal's quality certification and the announcement of funding opportunities for researchers. The text provides information about various activities and events organized by the Sociedad Española de Óptica (Spanish Society of Optics). These include grants for young researchers, interactive workshops on optics, dialogues with experts in optics and photonics, and tribute plaques for retired members. The text also mentions the celebration of the International Day of Light and the International Day of Color, as well as the awards ceremony for the Photon Awards. Additionally, it highlights collaborations with other societies and the upcoming International Year of Quantum Science and Technology. [Extracted from the article]

Copyright of Óptica Pura y Aplicada is the property of Sociedad Espanola de Optica and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The document is a newsletter from the journal "Óptica Pura y Aplicada" (Pure and Applied Optics) providing updates on the activities and initiatives of the Spanish Society of Optics (SEDOPTICA). The newsletter highlights various projects and collaborations undertaken by SEDOPTICA members, including support for the National Optics Meeting in Murcia, partnerships with sister societies, and conferences and interviews organized by the Women, Optics, and Photonics Area and the History of Optics Committee. The newsletter also mentions initiatives to strengthen the society's relationship with collaborating companies. Additionally, it announces upcoming events such as the National Optics Meeting in 2024 and the Justiniano Casas Research Award in Optical Imaging. The newsletter concludes with the announcement of the winners of the FOCUS awards for outstanding master's theses in optics and photonics. [Extracted from the article]

Dust particle artifacts are present in all imaging modalities but have more adverse consequences in medical images like retinal images. They could be mistaken as small lesions, such as microaneurysms. We propose a method for detecting and accurately segmenting dust artifacts in retinal images based on multi-scale template-matching on several input images and an iterative segmentation via an inpainting approach. The inpainting is done through dictionary learning and sparse-based representation. The artifact segmentation is refined by comparing the original image to the initial restoration. On average, 90% of the dust artifacts were detected in the test images, with state-of-theart restoration results. All detected artifacts were accurately segmented and removed. Even the most challenging artifacts located on top of blood vessels were removed. Thus, ensuring the continuity of the retinal structures. The proposed method successfully detects and removes dust artifacts in retinal images, which could be used to avoid false-positive lesion detections or as an image quality criterion. An implementation of the proposed algorithm can be accessed and executed through a Code Ocean compute capsule. [ABSTRACT FROM AUTHOR]

Copyright of Óptica Pura y Aplicada is the property of Sociedad Espanola de Optica and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

We consider the changes produced in the quality of eye fundus images of patients before and after cataract surgery with intraocular lens implantation and propose a measure to quantitatively assess those changes. Several factors concerning the optical system of the eye, the ocular media, and the specific characteristics of the implanted intraocular lens, may influence the quality of the digital image acquired with a non-mydriatic retinal camera. We illustrate our study with several cases taken from the clinical practice. A pair of pre- and post-operative eye fundus images represents each case. To measure image quality, we carry out a calculation of image anisotropy on each image. The results show that after surgery with intraocular lens implant, a fundus image is usually much brighter, sharp and higher quality. However, this rule of thumb can be altered by several conditions. For example, the multifocal design of the intraocular implant after a clear lens extraction. The anisotropy-based measure has revealed to be a suitable tool to quantitatively assess quality changes between pre-and post-operative fundus images. [ABSTRACT FROM AUTHOR]

A new unsupervised method for segmentation of objects of diverse nature with the common feature of connectivity (e.g. branching trees or net-shaped objects) is proposed. A preferred application to the vasculature segmentation of retinal images has been illustrated using images from DRIVE database. In the pre-processing stage, the method overcomes the common problem of non-uniform illumination of eye fundus images. The method follows with an iterative algorithm that starts with a seed and adds, at each step, a new vessel segment connected to the previously segmented part. The result preserves the connectivity as a distinct feature of the retinal vessel tree. The segmentation performance is evaluated through common signal detection metrics: sensitivity, specificity and accuracy. [ABSTRACT FROM AUTHOR]

This paper presents results of the research related with the development of the doctoral thesis of Lenny Alexandra Romero Pérez. This work covers the design, the characterization and the analysis of several programmable diffractive optical elements (PDOEs) such as: Fresnel lenses, multifocal lenses, integrated combinations of phase-masks with lenses, and DOEs with extended depth of focus (EDOF) like the Light Sword optical element and the Peacock Eye. This has been pursued to address several problems of human vision, like myopia, hyperopia, astigmatism, and presbyopia, by means of the implementation of such DOEs on a Holoeye Liquid Crystal on Silicon HEO 1080P spatial light modulator. We have developed and implemented several algorithms for generating the necessary optical elements to compensate the different ametropies. Simulation and experimental results demonstrate that several of the considered DOEs have the sufficient imaging performance and thus the potential for compensating ametropies and presbyopia. [ABSTRACT FROM AUTHOR]

Medical digital imaging has become a key element of modern health care procedures. It provides visual documentation and a permanent record for the patients, and most important the ability to extract quantitative information about many diseases. Modern ophthalmology relies on the advances in digital imaging and computing power. In this paper we present an overview of the results from the doctoral dissertation by Andrés G. Marrugo. This dissertation contributes to the digital analysis of retinal images and the problems that arise along the imaging pipeline of fundus photography, a field that is commonly referred to as retinal image analysis. We have dealt with and proposed solutions to problems that arise in retinal image acquisition and longitudinal monitoring of retinal disease evolution. Specifically, non-uniform illumination compensation, poor image quality, automated focusing, image segmentation, change detection, space-invariant (SI) and space-variant (SV) blind deconvolution (BD). Digital retinal image analysis can be effective and cost-efficient for disease management, computeraided diagnosis, screening and telemedicine and applicable to a variety of disorders such as glaucoma, macular degeneration, and retinopathy. [ABSTRACT FROM AUTHOR]

A new optical security system for image encryption based on a fractional joint transform correlator and nonlinear filtering is proposed. The position of the lens in the proposed optical encryption setup can be chosen, so that an additional key is introduced in the security system. The distributions at the input and output planes of the encryption system are related by a fractional Fourier transform (FrFT) at a given fractional order that is defined, among other parameters, by the focal length and the position of the lens in the setup; this fractional order acts as an additional key of the security system. The optical intensity of the complex distribution in the fractional Fourier domain (output plane) is captured by a CCD camera. The nonlinearity introduced in the last step of the encryption process, maintains the encrypted function as a real-valued function. The security system proposed in this work is an generalization of the encryption system based on a conventional joint transform correlator (JTC), from the Fourier domain to the fractional Fourier domain. Additional advantages of the proposed system are: new degrees of freedom for the optical setup, alleviated alignment requirement, and the introduction of an additional key (the fractional order of the FrFT) that improves security. Numerical simulations verify the validity of this new optical security system. [ABSTRACT FROM AUTHOR]